Delegation strategies for the NCLEX, Prioritization for the NCLEX, Infection Control for the NCLEX, FREE resources for the NCLEX, FREE NCLEX Quizzes for the NCLEX, FREE NCLEX exams for the NCLEX, Failed the NCLEX - Help is here. The 9.9 hp motors covered in this article, came into being in 1974. As for actual physical differences between the 9.9 and the 15 hp that you could use for identification other than the decal markings, year by year these 2 hp sizes and brands are the same.. The best boat forum for marine electrics and marine electronics for technical advice and answers. Share your experiences here..